All-suspension bicycle frame with isolated drive gear

ABSTRACT

A frame assembly for a two-wheel vehicle includes a front wheel fork and chainstays. Between the front wheel fork and the chainstays, the frame assembly further includes a saddle tube, a crank housing, and a lower tube connecting the crank housing to a steering tube. A parallelogram-shaped suspension assembly is attached to a rear end of the chainstays.

THE INVENTION

This invention pertains to a suspension system and power transmission ona two-wheeled vehicle, predominantly a bicycle or motorcycle. Moreprecisely put, the invention pertains to a suspension system for therear wheel and the power transmission, as well as a suspension forkassembly.

A DESCRIPTION OF RELATED TECHNOLOGY

There are a number of existing prior art suspension designs for bicyclewheels. Recent variations include one in which the entire powertransmission is mounted in the bicycle's rear frame triangle, alsocalled chainstays, which in turn are mounted to the main frame with ajoint. The suspension allows the chainstays to move relative to the mainframe, provided the chainstays have been joined at an appropriate pointto the main frame. It follows that as the rearwheel hits a bump, theentire rear triangle of the bicycle will change its position relative tothe main frame, thus isolating the main frame from the impact. Theimpact, in other words, does not transplant itself to the rider throughthe saddle, the pedals or the handlebar. The chainstays are typicallyjoined to the main frame with a bearing placed close to the crankset. Inseveral variations of this construction, the chainstays are joined tothe main frame at a higher point, closer to the crossbar.

The advantage of this type of construction is that the suspension doesnot affect the power transmission apart from shuttling the lower part ofthe bicyclist's legs back and forth. The disadvantage of this type ofconstruction is a considerable shaking of the bicyclist's feet and legsat high speeds. Another disadvantage is the generally upwards movementof the rear wheel and chainstays upon hitting a bump in the road. Thisoccurs due to the relatively small difference in altitude between thejoint where the chainstays are mounted to the main frame, and the rearhub. Upon making contact with the bump, the wheel will move upwards inan arc defined by the hinge. This is only desirable if the bumps arerather small, thus making contact very low on the wheel. These smallbumps will propel the wheel slantingly upwards and backwards. Thesmaller the unevenness in the road, the more the force exerted on thewheel will be directed upwards. On the other hand, upon hitting a largerbump, the rear wheel movement will be considerably steeper than thesteepness of the forces acting on the wheel. The angle between theground and the direction in question will be close to 60 degrees. In theaforementioned construction, this will result in the shock being, to aconsiderable extent, transported to the bicyclist through the saddle,suspension system notwithstanding. This is the case for all relatedconstructions, apart from those where the chainstays are joined to themain frame a considerable distance above the crankset, resulting in abetter absorption of larger humps. This works rather well, provided nopower is transmitted to the rear wheel. Should this occur, the contactlocation between the rear wheel and the surface will be displaced inrelation to the bicyclist, as the horizontal component of the wheel'sup-and-backwards movement will have to displace something, in this casethe bicyclist on his/her saddle. For all practical purposes, thisresults in a compromise between displacement of the bicyclist andreduced suspension. (Provided the rear wheel is kept firmly on theground, and does not start spinning.)

This effect will occur with all single-jointed constructions as thewheel will rotate to the same degree as the chainstays will rotate inrelation to its joint with the main frame. This rotation will occur inaddition to the existing rotation and propulsion of the rear wheel, andto the change of distance between the main mass (the bicyclist) and thewheels' point of contact with the ground, and will result in an attemptto accelerate the bicyclist in order for suspension to occur. This,however, involves a significant amount of energy, and the system as awhole is forced to compromise (provided this accelerations' increaseddemand for friction against the surface does not cause the rear wheel tolose its grip), by partly providing suspension, and partly lifting thebicyclist up.

Attempts have been made to solve this problem by mounting the chainstaysto the main frame with a parallelogram-like contraption, rather thanutilizing a single-jointed system. This works excellently as far as theaforementioned problem goes, as the wheel's orientation is heldconstant. The wheel's surface grip does not become subject toundesirable forces due to additional rotation. This structure typeincludes, together with single joint structures, constructions in whichthe drive gear is not isolated from the rest of the bicycle by beingsuspended entirely in the rear triangle. The drawback of thisconstruction is the resulting variable distance between the topmost partof one of the (most commonly) three cogwheels of the crank set, and theupper quadrant of the corresponding cogwheel on the freewheel. Thisleads to a stretching of the chain, exerting power which in its turnsaps the energy the bicyclist is utilizing to propel the vehicleforwards. This is the problem which bicycles with isolated powertransmission try to eliminate. Furthermore, the wheel's directionimmediately after impact with a bump on the surface remains unfavorable.Furthermore, should the suspension characteristics of any system besubject to a desired change, the only way to achieve this is byreplacing the spring itself or, in some cases, taking the suspensionunit completely apart and mounting it in a different position.

A general drawback and limitation that all full-suspension solutionspresently suffer is a comparatively large amount of weight which remainsunsuspended. Gears, cogwheels and chain are all forced to movesimultaneously with the rear wheel, brakes and a rather heavychainstays-construction. An ideal function such as bicycling overmedium-sized bumps at high speed is not possible with this type ofconstruction, for two reasons. Firstly, the chain and rear changer areforced to move with the wheel, making the chain rattle to and fro andprovoke unexpected changes of gear. This situation admittedly rarelyoccurs, as friction in the suspension device is usually amply provided,drastically reducing the velocity of the rear wheel as it, along withthe chain and rear changer, hits a bump in the road. Rather, thebicyclist again is forced to absorb the shock through the saddle, asexcessive friction in the system prevents the spring in the springingmechanism from compressing, which is caused by the speed with which, forexample, oil is pressed through a valve too high for the reciprocalpower to provide sufficient suspension for the bicyclist. On so-called“downhill bicycles” various steering wheels are often mounted to preventthe chain from jumping off the cogwheels. The disadvantage of this, andrelated solutions, is the reduction of the number of gears by 66%.

Secondly, the suspension constant is not subject to change while in use.Certain constructions are equipped with the ability to “turn off” thesuspension entirely by sealing off the valve oil in the suspensionsystem. A gradual reduction of the suspension is also possible,resulting in an effect corresponding to installing a stiffer spring inthe compression chamber of the system. However, this much friction orsuppression prevents the rear wheel from returning to its intendedposition in time to absorb the shock from the next bump in the road(unless this is situated several meters away).

There are a number of existing prior art suspension designs for abicycle front fork. The most common is the device with telescopic jointaction in both fork legs. The prior art also comprises a design which isdisclosed in U.S. Pat. No. 5,462,302, in which both legs of the fork aresupported in a parallelogram which is oriented forward relative to anormal type of fork. Such a design will not provide any “anti-dive”feature. This means than under breaking, the suspension system isactivated causing the front end of the bicycle to dive forwards anddownwards. This is not desirable. The same construction is also known tobreak under pressure from the side. There also exist prior art variantshaving hinged double fork legs, such as U.S. Pat. No. 5,431,426, U.S.Pat. No. 4,421,337, DE-A-38 33 880 and DE-A-39 29 812, and also varioussingle-legged fork constructions. A problem all these fork constructionshave in common, is that it is imperative to take them apart, replace thespringing medium with another one, such as a stiffer spring, to attain asatisfactory result based on the individual bicyclists weight andpreferred cycling style.

The best-known designs normally have high friction under the transfer offorces to the springing medium. The prior art also includes variouscomplicated linkage designs, often in connection with motorcycle forks.Examples are EP-A-30,306, 32,170 and 10, 426. These solutions willnormally be poorly suited to bicycles.

From EP-A2-493,773, we are familiar with a suspension front fork inwhich a linkage arranged in a parallelogram form, with stays angleddiagonally downwards and backwards while connected to a coil spring,results in a suspension and dampening mechanism. However, thismechanism, which is not very clearly described in the document, eitherprovides too small a range of fork travel, or is structurally weakregarding torsional forces. In addition, it is unclear how thesuspension means can work as intended. According to the publication itis furthermore dependent on a pipe which in a traditional manner goesdown through the frame's front steering tube, mounted in the headsetbearings, in order to provide a basis for a forkholding device formounting of parallel bars. This applicant's Norwegian patent applicationnumber 1996 2355 concerns a solution with one central bar, twosupporting bars and an enclosing structure. This solution requires aconsiderable amount of space under the fork crown in order toaccommodate the middle central bar, as well as ample dimensions andweight for parts which are to absorb shock.

SUMMARY OF THE INVENTION

The following invention comprises a fully suspended bicycle frame whichabsorbs unevenness of reasonable dimensions at realistic speeds ofoff-road bicycling, far better than the constructions offered today.Furthermore, all suspension-related problems concerning the movement ofthe power transmission relative to the frame are entirely avoided, whilesimultaneously offering improved suspension as such. Additionally,adjustment of spring constant is infinitely variable with a simple knobor screw. Adjusting the spring constant can be performed whilebicycling. The purpose of the invention is to present a light and solidconstruction of high durability, which needs only a limited amount ofmaintenance.

The main aspect of this invention is a frame with an isolated primarypower transmission and an assembly with a secondary power transmissionfor transferring power to the driving wheel. Also included is asuspension, the assembly of which encompasses the components describedin the following.

A frame with a hold component for holding a suspension mechanism and adrive gear on a projection or structure (chainstays) reaches, on one orboth sides of the rear wheel, backwards towards the rear wheel's hubfrom an appropriate point on the frame. For all practical purposes, anormal freewheel or cogwheels are provided for gearing, but without arear stop, they are mounted into one of the bearings on the movablemidsection or to a hold on the main frame's rear structure or on theoutside of the bearings on the rear section's one holding section linkedto the main frame's rear section. Alternatively, they are mounted on oneof the aforementioned bearing bolts, linked to the main frame's rearstructure, resulting in a fixed distance during suspension, typicalplacing for freewheel, lower bar and lower mounting on the frame's rearand hub bearing without a rear stop mounted to the same bar as thefreewheel.

A movable rear section includes one, two, three or more bars, somewhatparallel, pointing slopingly downwards, each mounted in revolvablebearings at both ends.

One or several suspension mechanisms are placed mainly in the movablemidsection in order to create an upwardly-directed spring force towardsthe frame and the rider, where the suspension mechanism is equipped witha system for regulating the suspension mechanism's effective springconstant (spring stiffness). Also, torsion springs can be mounted aroundthe bearing bolts, and the arms of the springs supply a counterforce byincreasing or decreasing the angle between them. These can be combinedwith suspension springs as desired, to, for example, economize on space.Another type of additional suspension could be a rubber spring in orderto achieve a progressive supplement to the main suspension, or toprovide an optimal smoothness at the end of suspension movements whensubjected to considerable challenges. The springing media compresses ina defined area of a lower bar, and springing media 25 placed inconnection to a rear wheelholder in the ultimate sequence of maximumsuspension release will provide the same spring constant regardless ofthe springing constant chosen for the main media. Mounting componentsfor disc breaks on the rear wheel are also provided.

A preferred embodiment of the invention includes a suspension mechanismwith a linearly functioning spring, of which at least one end issupplied with a device which can be adjusted transversely relative tothe spring's linear direction. In this preferred embodiment, thelinearly functioning spring's transversely adjustable device is ideallysituated in a compartment placed next to the hub-supporting structurebetween the bars, as the springing mechanism's other end is mounted inthe vicinity of the frame's rear section or in the movable end section'sother end, either in connection to one of the bearings on theaforementioned or outside. The compartment can, of course, be mounted inany end of the movable rear section. The movable rear section with thespring and power transmission can be a part of the bicycle frame on justone side or on both sides of the bicycle's rear wheel.

In one embodiment, a pre-tensioning screw is preferably mounted forpre-adjustment of the spring, and a stopper device can be mounted tolimit the upwards deflection caused by the pre-tensioning. In anotherdesired embodiment, the spring mechanism (or mechanisms) on the movablerear section are supplied with known stoppers and end limiters of thespring deflection, pertaining to the telescopic movement of thesecomponents.

In an alternative embodiment of the invention, the spring mechanismincludes at least one torsion spring placed around one of the bearingsor another place where the arms meet counterforces, such as on theinside of the bars, and includes another counter-support in a suitableplace. The torsion spring can be a permanent, unadjustable supplement toincrease the spring constant by an arm engaging an adjustable extensionon one or both bars.

In this second variant, the torsion spring with an adjustable effectivespring constant can be positioned on the inside (beneath the upper bar).

There is a possibility, in this embodiment, to mount a counter-supportfor the torsion spring's (or springs') arms in such a way that thecounter-supports can be removed from engagement upon the torsion springby pulling a wire by way of a lever on the handlebars, in order toincrease the spring constant should this be deemed necessary.

In the alternative embodiments of the invention, a prestressing screwcan be placed for advance tightening of an arm on the torsion spring,and a stopper can be placed to limit the upwards deflection caused bythe prestressing (biasing).

In a third alternative embodiment, pre-tension (biasing) could beachieved by reducing the torsion spring's arms by tightening a threadedpart mounted on a sheath with a guide for the spring arms on the insideof one of the top or bottom of the parallelogram bars.

In any of the embodiments, the suspension mechanisms can include atleast one additional torsion spring mounted around one of the bearingsto provide a larger total spring constant. For the sake of economizingon space, a combination of these possibilities can also be considered.

The front assembly of this invention presents none of the previouslymentioned disadvantages, and is created for use on any bicycle (ortwo-wheeled vehicle). The suspension mechanism can be preciselymonitored and adjusted by a hex key or knob. Too high or too lowpre-tension is thus avoided, as are complicated procedures forreplacement of springs. Using a wide and torsion-resistant bar, thenumber of components in the setup is drastically reduced, along withproduction costs. Furthermore, a flat tire can be repaired withoutremoving the wheel from the bicycle. Thanks to the cost-efficiency of anasymmetrical construction, the possibility arises of using durableballbearings without making the construction too heavy.

Another aspect of the invention is thus related to the mounting of asuspended front fork of the asymmetrical type, for use on a standardsteering tube. Mounting involves a frontal fastening board which can bemounted to the steering tube with revolvable bearings on the top andbottom of the steering tube. On the side of the fastening board iseither a downwards-facing fastening part for a bar and suspensionmechanism in which, for example, the wheel is fastened in a pipe whichjuts outward and downward from the suspension mechanism, or a longer,downwardfacing fastening part shaped as a pipe in which the bar andsuspension mechanism are mounted at the extremity, and where forexample, the wheel's hub is integrated as part of the suspensionmechanism. By placing the suspension mechanism between these points, acombination of the pipe and fastening parts is a possibility. In bothcases, at least one of the bars is slanted downwards and backwards,relatively broad and torsion-free. The configuration can make up aparallelogram to keep the orientation of the wheels or disc brake padsconstant independent of braking. The direction of the bars, and the factthat the orientation of the wheel can be upheld or altered as onewishes, gives the set-up an anti-dive function. The construction,correspondingly, is made up of at least one torsion-free bar and ifdesirable, additional bars to maintain the wheels' orientation or toincrease torsion rigidity. The bar or bars are pivotably mounted at bothends and have a predominantly different length with a suspensionmechanism placed in such a fashion that the suspension system will alterthe distance between the suspension system's anchorage points. Thesewill either approach each other, or they will go in opposite directions,allowing suspension power in a springing medium to be utilized forabsorbing a bump. In those cases in which an additional bridge has beenfastened to the fork pipe for mounting standard (non-disc) brakes, morethan one bar will not be necessary as the forkpipe itself guaranteessatisfactory orienteering of the wheel and the brake pads which operateon the wheel's rim. This only applies, of course, in those cases wherethe suspension mechanism is placed above the brakes' mounting points. Anadvantage of placing the suspension mechanism low on the wheel is theincreased prospect of acquiring an antidive-effect through the correctposition and length of the bar which defines the relationship to thedisc brake pinching device and how it affects the brake disc. Antidivecan also be acquired by positioning the suspension mechanism higher up.

The mounting of the fork, according to this invention, is recognized byhaving one leg only. At least one broad bar is mounted on horizontalaxle pins on the fastening part, and fastened to a fastening part onfastening boards for the forks steering pipe (FIG. 1 is known fromstandard forks), or fastened to an external structure (FIG. 2 known fromNorwegian patent application number 1996 2355) on its fastening part onone side of the bicycle's front wheel. The bars comprise at least onebroad bar mounted on one side of the bicycle's front wheel, respectivelyrevolvable and in pairs on horizontal shafts or axle pins in the rearfastening structure for the parallelogram-bars. The width and mountingof a relatively large bar results in a torsion-rigid structure.

A suspension mechanism is mounted in such a way that the movements ofthe suspension system will alter the distance between the suspensionmechanisms anchorage points, which move towards, or apart from, eachother. In this way, suspension power in a suspension medium can beutilized for absorbing bumps, and the suspension mechanism includes alinearly functioning spring in which at least one end of the spring isfitted with a device which can be altered relative to the spring'slinear direction. By turning a hex key or a similar tool, at its fixedbase, rotation will cause a displacement of the transverse bolt to whichone end of the spring mechanism is attached. The displacement of thetransverse bolt in relation to the same extremity's rear fasteningpoints for parallelogram-bars will alter the suspension characteristicsin the suspension mechanism as the difference in the distance betweenminimum and maximum deflection of the transverse bolt's position will besubject to corresponding travel of the fork. Yet another suspensionmedium has been added at a suitable position for compression of adefined area, and independently adjusted to provide a progressive andsmooth rounding-off when the system is exposed to large bumps.

Adjusting suspension characteristics has long been a problem. Mostsystems involve a more or less intricate oil-based dampening mechanism,as well as the option for altering bias and suspension characteristicsby replacing the suspension medium.

This problem is solved in this invention, as the spring compression canbe altered to adjust the suspension characteristics to a desiredresistance pr. mm. suspension. This is achieved by transposing theplacement of one end of the suspension mechanism along a slot placedbetween the bearings' mounting holes in a slotted compartment, placed ina direction which is mainly perpendicular to the suspension mechanism'shorizontal axis, as seen in an unloaded state. As the parallelogramsswing upwards and backwards during loading, the difference between thesuspension mechanism's upper anchorage point and any other placement ofthe suspension mechanisms other end along the slot will have a desireddifference corresponding to the same movement of the suspension system.Furthermore, an adjustment knob is placed on the suspension mechanism.

It is often attempted to dampen undesirable rocking movements bysupplying the movable parts with friction against each other somewhereand to a controllable degree. The submitted invention has solved this byutilizing the possibility for precise adjustment of the suspensionmechanism in such a way that the counterforces in the spring do notsurpass the counterforces represented by the bicyclist and the bicycle,while simultaneously minimizing friction and providing a favourabledirection of the wheel at the initiation of each movement. Together,these characteristics ensure that virtually no movement is transplantedto the handlebars, which provides the bicyclist with an upwards thrust.Accordingly, there will be no mass in need of suspension. This appliesto most situations at most speeds. In certain occasions, where bumps andvelocity demand a stronger spring for shock absorption, a supplementarysuspension medium has been included in addition to the main medium. Atlow speeds, low weight, and simple manuvering, no additional friction tothe suspension system is required. Quite the contrary, as long as thespring is soft enough and the speed and weight are low enough, nomovement will propagate through the handlebars. Should this occur, nosuspension is needed anyway, as there is no mass in movement. For thisreason, no dampening mechanism is included in the present embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described more closely in a detailed description ofenclosed drawings in which:

FIG. 1. is a side view of a bicycle with chainstays and a fork inaccordance with a preferred embodiment;

FIG. 2. is a plan view of the rear portion of the bicycle in FIG. 1,enlarged to show important details;

FIG. 3. is an enlarged detail view of the suspension system for a rearwheel, as shown in FIG. 1;

FIG. 4. is a front view of a one-sided front fork in accordance with oneembodiment of the invention;

FIG. 5. is a side view of a suspension mechanism for the front fork inaccordance with one embodiment of the invention;

FIG. 6. is a side view of an alternative embodiment of a front forksuspension mechanism;

FIG. 7. is a plan view of a bicycle with a one-ended fork embodiment infront as well as at the rear;

FIG. 8. is a plan view similar to FIG. 2, in which power transmission bychain has been replaced by gimbals.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1–3 show a preferred embodiment of one aspect of the invention. Arear frame construction 2 includes a lower wheelholder 5 for rear wheel4, rear fastening part 3 attached to a main frame 1, one movablemidsection formed of bars 6, 7, between wheel holder 5 and fasteningpart 3, and the frame itself 1 for supporting the remaining parts whichtogether comprise a bicycle (i.e., a two-wheeled vehicle). As shown inFIG. 1, the main frame 1 includes chainstays 15, saddle tube 18, crankhousing 25, and a lower tube 26 connecting the crank housing 25 tosteering tube 116.

Rear fastening part 3 should be mounted on the chainstays (chain fork)15 of the main frame 1, and they strengthen the chainstays 15 withmounting details because the rear fastening part 3 has holes forthreaded inserts for the fastening of bearing bolts 21, 22 as well asthreaded parts for mounting of gears. Fastening part 3 forms a rigidextension of chainstays 15.

The bicycle's rear wheel 4 is mounted on the lower wheelholder 5 witheither the bearing bolt 19 or 20, or is fastened to bolt 19 or 20, andwheelholder 5 forms a rigid extension of movable midsection includingtorsion-rigid bars 6, 7. Rear fastening part 3 and lower wheelholder 5have been designed so that bearing bolts with cogs or bars can bescrewed directly into this structure from the side.

Between rear fastening part 3 and rear wheelholder 5 is the movablemidsection made up of the two mainly parallel bars 6, 7 of predominantlyequal length, and one or several suspension mechanisms which eventuallycan comprise a dampening unit. The upper bar 6 is fastened at each endby upper bearing pins 22, 20 to rear fastening part 3 and lowerwheelholder 5, respectively. A suspension unit, such as a spring 12, hasbeen fastened to bearing bolts 22 and 19 on rear fastening part 3 andlower wheelholder 5, respectively. In FIG. 3, however, an adjustablemounting on bearing 19 (i.e., the spring 12 itself) is described infurther detail below.

The mainly parallel bars 6, 7 can pivot around bearing bolts 19, 20, 21,22 (as applicable) and if the center distance between the bearing boltsalong each of bars 6, 7 is identical, or if in addition the distancebetween the center points of the bearing pins on rear fastening part 3and lower wheelholder 5 is the same, the movement of the movablemidsection (bars 6,7) will be “parallelogram movement” (i.e., the bars6,7, the rear fastening part 3, the lower wheelholder 5 and bearingbolts 19, 20, 21, 22 form a parallelogram-shaped suspension assembly).In other words, lower wheelholder 5 will maintain its orientation duringmovement in the suspension, so that no additional rotation of the wheelwhich could affect the power transmission in an unfavourable way duringbicycling over bumps will occur.

The bars can have somewhat different lengths, and the distance betweenthem can also be dissimilar. This might cause a relative backwardsrotation of the wheel, which affects the horizontal, backwards-turneddistance component which occurs as the movable midsection moves duringsuspension-related movements, and can be compensated for by a lengthcorresponding to the backwards rotation. (Cases such as this one, inwhich a slight deviation from a perfect parallelogram structure occurs,are nonetheless included when “parallelogram movement” is mentioned.)

Furthermore, a preferred embodiment includes a main frame withchainstays 15 only on one side (i.e., an asymmetrical construction asshown in FIG. 2). However, a more traditional embodiment withtraditional chainstays is also possible. For the sake of clarity,certain details have been omitted in FIG. 2.

A great advantage of the preferred embodiment with asymmetricalchainstays 15 and adherent powerfully dimensioned bearing bolts 19–22 inthe suspension device 2, is the easy access to the rear wheel from theother side where fork constructions would be an impediment. For thisreason, the desirable type of brakes would not be the traditional“scissor-kind”, and lower wheelholder 5 is accordingly equipped withdisc brakes. In FIG. 2, the brake disk 17 is rigidly mounted to the samerotating axle as the wheel. In other words, brake disc 17 rotatestogether with the wheel. On the lower wheelholder 5 is an extension (notshown) with brake pads which can grip a part of brake disc 17. The padsare manipulated in the customary fashion, through brake levers on thehandlebars.

As one can see, wheel 4, or the tire on the wheel rim, can be handleddirectly from the “open” side, (i.e., the side without rear frame 2) andcan be removed/changed without having to remove or manipulate otherparts. Changing wheels and tires can thus be performed with little timeor hassle. The wheel can be held firmly in its place on the axle with asnap-lock device (not shown).

An important aspect of the invention is the rear fastening part 3, wherea, for all practical purposes, normal freewheel 16 has been mounted. Anormal chain runs through this freewheel, and a change of gears occursin a normal fashion. The freewheel 16, however, is without a “rearblock” (i.e., it rotates freely in both directions). The freewheel 16also has a first cogwheel 11, in FIG. 2 shown closest to the wheel 4.This first cogwheel 11 is connected to second cogwheel 14 by a secondarychain 13 which is only shown in FIG. 1. Second cogwheel 14 is thedriving cogwheel for the rear wheels, and has a rear block to make upfor the missing rear block on the freewheel 16.

The freewheel 16 will typically be found between the extreme width-wisepoints of the lower or upper bars 6, 7, or in association with one ofthe bearings on upper or lower bar 6, 7, or on a separate bearing bolton this part and correspondingly on the lower wheelholder 5. An indentcan be provided to make a place for the cogwheels to rotate. It is ofutmost importance that the bearing pins/bolts for mounting the secondarychain 13, which might be placed on the outside of the bearing bolts forrotation of the midsection as a whole, have the same distance inrelation to the bearing pairs on the section, so no change of distanceoccurs during suspension which would cause a change of the chainsdistance and thus pedalfeedback. The suspension mechanism may also haveadditional torsion springs around one of the bearing bolts with aconstruction on the holding section and, for example, one of theparallelogram bars. An embodiment of the invention can also have severaltorsion springs around several or all of the four bearing bolts 19–22.Each torsion spring may engage a counter-support which can be shoved inand out by using a lever on the handlebars in order for an increasedsuspension constant to be added to the system with a simple movement ofa lever in demanding circumstances, such as steep downhill runs.

The suspension mechanism shown in FIGS. 2 and 3 is conceived as acompression spring 12. An extension spring, however, or other suspensionmedias can also be utilized. This type of spring is also suitable forbeing installed in the compartment for adjusting the system suspensionstiffness.

Bearing bolts 19–22 are predominantly equipped with threaded flanges tokeep bars 6, 7 in place. The bearing bolts' rather substantial diametermakes them resistant to development of play. In addition, ample space isallowed for ball bearings, should these be desired. (The broad line inFIG. 2 only pertains to the central axis of bearing pin 21, whosediameter is as indicated on both sides.)

Another important aspect of the invention can be witnessed in FIG. 3 inwhich, a suspension mechanism with an adjustment device for adjustingthe effective spring constant for the system as a whole is shown. Thesuspension mechanism and its central components can be fitted betweenone or several points which either approach each other, or separate fromeach other as the system moves in one direction. For example, fixedpoints on bars 6, 7 or a point on upper bar 6 and another one on lowerwheelholder 5, or a projection of one of the holding parts or the barsfitted for this purpose. This is something completely different than thepretensioner (i.e., pretensioning wheel) 24, whose only purpose is tomake sure spring 12 works in an area outside of its relaxed position. Inconnection with the suspension mechanism's lower terminating hold 9, aslot 8 has been provided for changing the position of one of thespring's ends, through a mainly transversal shift relative to thesuspension mechanism's (i.e., spring's) general direction. Instead ofone slot 8, one two slots might be provided, including one in each endof the suspension mechanism. One might, of course, also have two or moreholes to which one or both of the suspension mechanism's terminal gripscould be fastened. By doing this, one alters the spring stroke lengthduring a compression of the system as a whole. In this way, the springwill be pressed more or less together with the same deflection as thesystem as a whole. The spring constant (spring stiffness) relative tothe system as a whole will thus be altered to the extent one adjusts thegrip (or grips) of the spring mechanism in slot 8 with adjusting knob(adjusting device) 10 or a similar device. This adjustment mechanism caneither be a part of the rear wheelholder 5, or a separatecartridge/compartment with optional functions like change of bias, forattachment to one of the bearing bolts of the rear wheelholder 5, orother suitable mounting arrangements.

Whether one prefers spring mechanism 12 with an independently adjustablepre-tension with a separate pre-tensioning wheel 24 or not, anembodiment of the invention may have adjustable pre-tension by allowingthe compartment part to be swung around one of the bearing bolts 19–22on the rear fastening part 3 or lower wheelholder 5. One could alsoimagine a different arrangement in which a device is placed in asuitable spot for the adjusting knob's counter support. In this way, itwould be possible to change pre-tension by swinging the entirecompartment around a bearing bolt, such as bearing bolt 19, provided afixation stopper is provided for parallelogram bars 6,7, such as anelongation of the compartment towards the grip of bars 6,7. Thepre-tension can also be altered as the suspension mechanism is equippedwith the revolvable pre-tensioning wheel 24 which compresses spring 12while at the same time the angle of the parallelogram bars are keptintact by a counter-support inside the suspension mechanism whichprevents the distance between the suspension mechanisms end points fromincreasing.

By introducing a corresponding compartment cartridge for regulating theother end of the suspension mechanism, one has provided as manypossibilities for individual adjustment as are feasible. The suspensionmechanism's and the compartment's location can be outside the movablemidsection's limitations, wherever two points move towards each other orapart during suspension of the system, to give space for a spring whichis as long as possible. Furthermore, one may mount a suspensionmechanism based on the compression of air, where the system's springconstant is regulated by the pressure of the pneumatic springs. Acombination of the systems is, of course, also possible, such as acombination of systems for regulating the stiffness of the pneumaticspring by altering, as described above, the relationship between thesystem's movement and the deflection affecting the spring.

As mentioned above, the hub cogwheel 11 for the rear wheel 4 is equippedwith a rear stop (instead of the freewheel 16). In addition a rear stop23 on the longer wheelholder 5 is of importance. These two rear stopsprevent rotation in diametrical directions. The rear hub is tightenedduring power transmission, the bearing grips the hub, which in turn isconnected to the wheel's contact point. One can therefore both pedalbackwards or refrain from pedalling.

In the case of lower wheelholder 5, the rear stop 23 will rotate thehub's cogwheel 11 (with its hubstop) some degrees backwards, thusaltering the orientation of the wheel somewhat, and preventing thewheel's contact point with the surface to change horizontally relativeto the main mass of the bicycle and rider. What happens here is acompensation for the extension of a slanted arm as it is straightenedbackwards, changing the point of engagement of the wheel, thereby tryingto thrust the bicyclist in a forward direction. This situation isconsequently prevented, and in a practical case this is of greatimportance.

In another aspect of the invention, the normal chain between the vehiclecrank set and rear freewheel 16 is replaced with a cardan transmissionmechanism including gimbals. This is demonstrated in FIG. 8. As shown inthe mechanism includes a rear cogwheel 30 on the gimbal sheaths 34, 35,a shaft 31, and a holder 32 having a guide bar for gearing. Themechanism further includes a holder 33 having a pin for the guide bar, agimbal shaft 36, is another holder 37 with a guide bar for gearing, yetanother holder 38 with a pin for the guide bar, and is a second cogwheel39, situated by the gimbal front end.

To change gears, the gimbals pull cogwheel 30 or 39 out of mesh withfreewheel 16 or a cogwheel on the crank set, shuffling to a larger orsmaller cogwheel on the freewheel or on the crank set. Thereafter, aspring is released which forces the gimbals' cogwheel to mesh with theselected gear. To achieve this, the gimbal shaft is elongated duringgearshifts, and has a different length depending on the chosen gear. Forthis reason, the gimbal shaft is split in two halves, each with theprofile of a half moon. Between these there is a roller bearing, whichmakes it possible to shift length while transmitting power. One end ofthe gimbals can be joined directly to a freewheel on the hub or, asshown, to the freewheel 16, with power transmission by way of a chain 11from the freewheel 16 to the hub cogwheel 14. The advantages of usinggimbals is a simplification of the gear system, less maintenance, lessmess, and there is no chain which can jump off the cogwheels.

By placing the rear cogwheels of the gimbals towards a selected cogwheeland gear in the same way a chain is applied today, a minimum number ofcogwheels are in contact with each other, thus minimizing friction,which is the point of this solution. All other gimbal-based solutionsresult in higher friction.

Another aspect of the frame construction is the fork which can be seenin FIG. 1, mainly on the right hand, and also FIGS. 4 and 5. (FIG. 5illustrates the same portion as FIG. 1, but enlarged.)

The most important characteristic of the fork is that it is one-sided,but it will still offer suspension.

FIG. 5 shows the fork separately, in profile, and the various detailswhich are included will be discussed from top to bottom. This figureshows a frontal piece 109 and steering tube 116, and a headset fastenedeither to an extension (not shown) of the frontal piece 109, or to astandard, extended inner steering tube which extends above the bicycle'ssteering tube assembly. A fastening piece 105 has a downwards protrudingsection 111 on the side of the bicycle front wheel 100, and two bars101, 102, at least one of which is broad and strong, are pivotablymounted on horizontal shaft pins 120, 104 on a support 103 for the forkleg 107. The support can be part of a piece mounted to the fork leg 107,or an integrated part thereof. The width and mounting of a comparativelylarge bar 101 provides a torsion-rigid construction.

FIG. 4 shows a fastening piece 105 with a downwards protruding section111. The movable pair of bars 101, 102 are shown mainly on the outsideof the fastening piece 105. An external structure, encompassing theexterior of the two bars, is also a possibility.

Both bars 101, 102 point downwards and backwards from the mounting-pointin the downwards protruding section of the fastening piece, and relativeto the bicycle's forward direction. Upper and lower bars preferably havedifferent lengths so that the lower bar 102 may be somewhat shorter thanbar 101. Lower bar 102 is preferably placed more or less on the samelevel as the front wheel tire.

The upper, frontmost bearing pin 122 for the upper bar 101 may befastened to the downwards protruding section with, for example, athreaded unit in one end for mounting in a correspondingly threaded holein section 111.

Another important aspect of the invention is a suspension mechanism witha system for adjusting the effective spring constant for the system as awhole. The suspension mechanism and its central components (inparticular spiral spring 112) may be placed between two points whicheither approach each other or move apart as the system moves, forexample, fixed points on section 111 and support 103, or a point onupper bar 101 and another point on rear support 103, or a projection onsection 111, support 103 or bars 101, 102. This is something completelydifferent from the pre-tensioning of spring 112, which can be effected,for example, with a pre-tensioning wheel 24, whose only function is tomake spring 112 work in an area outside of its relaxed position. (Spring112 is not shown in FIGS. 1 and 5, but is placed next to part 124 on theoutside of the steering and stopping device 118.) A slot 108 has beenplaced in connection with the suspension mechanism's lower fasteningpoint, and has a mainly transversal displacement with regard to thesuspension mechanism's general direction. Instead of one slot, two slotsmight be included, including one in each end of the suspensionmechanism. One might, of course, also have two or more holes where oneor both of the suspension mechanism fastening points may be mounted. Inthis way, the stroke length of spring 112 may be adjusted by a givencompression of the system in its entirety. Thus, the spring is pressedmore or less together with the same deflection for the system all inall. The spring stiffness/constant relative to the system as a wholewill thus be altered depending on how one chooses to adjust one (orseveral) fastening points for the suspension mechanism in slot 108 withan adjusting knob 110 or similar. This mechanism for adjustment caneither be a part of support 103, or can be stored in a separatecartridge or compartment 106 (see FIG. 6), conceivably with additionalfunctions such as adjustment of the pre-tension, can be fastened to oneof the bearing bolts 120, 104 or other appropriate fasteningarrangements. Whether one desires a suspension mechanism withindependently adjustable bias with a separate pre-tensioning wheel 124or not, one embodiment of the invention may provide an adjustablepre-tension by rivoting compartment 106 around one of the mountedbearing bolts, in FIG. 6 bearing 119 provided a fixation stopper existsfor the parallelogram arms, such as an extension of the compartmentmeeting the ceiling in one of the bars 101, 102. The bias may also, asmentioned, be altered by equipping the spring mechanism with arevolvable pre-tensioning wheel 124, which presses the spring 112together while simultaneously retaining the angle of the parallelogrambars 101, 102, allowing a counter-support inside the suspensionmechanism to prevent the distance between the suspension mechanism's endpoints from increasing.

In FIG. 4, reference numeral 117 pertains to a braking disc. A discbrake is an advantage here, as with the rear wheel.

FIG. 6 shows another variation of the suspended front fork of theinvention. Specifically, it shows a version in which the suspensionmechanism has been moved to a position closer to the front wheel hub,such as at the bottom end of the fork leg 107. In this embodiment, thelower bar 102 is wide strong (which is better to take up torsion forces)while the upper bar 101 is slimmer. The fork leg 107 tapers out to part121, and bars 101, 102 are journalled between this tapering part 121 anda wheelholding unit 123 (analogous to support 103 for the fork leg inthe variant with the suspension mechanism placed higher up.)

The top part of the fork leg (not shown in FIG. 6) appears to be rathernormal, apart from its one-sided shoulder/crown beneath the frame'ssteering tube.

The function of the suspension mechanism placed low on the wheel isanalogous to the first variant, also concerning the adjustment of springstiffness by the aid of an adjusting knob 110 for transversedisplacement of the end attachment for the suspension mechanism (spring112) in slot 108 in a compartment 106 (which might eventually alsosupply the possibility of adjustment of pre-tension as described above).Note that in the shown embodiments, the parallelogram configurationdeviates to some extent from a perfect parallelogram, as the length ofbars 101, 102 are different. In the shown example the bars are, for thisreason, only roughly parallel.

FIG. 7 shows a complete, one-sided (asymmetrical) bicycle in accordancewith important aspects of the invention, seen from above. Note theone-sided fork and chainstays 15 and 107, and brake discs 17 and 117.

The various aspects of the invention may be combined, or implemented tovarying degrees, on a bicycle. The preferred version is entirelyone-sided and has a parallelogram suspension with an adjustable springconstant on both front and rear end of the bicycle, but one-sidedness oneither of the ends is sufficient. Furthermore, a parallelogram-typesuspension with an adjustable spring constant on either the front orrear of the bicycle is also sufficient. (Regarding the chainstays,adjustability is not a necessary feature.)

Only a human-powered bicycle has been described herein, but somepossible embodiments are feasible for motorcycles, and the inventionconcerns two-wheeled vehicles in general.

The invention has been described above using, in a non-restrictingmanner. The scope of the invention shall only be subject to thelimitations of the enclosed claims and equivalents of these.

1. A frame assembly for a two-wheeled vehicle, comprising: a front wheelfork; a main frame attached to said front wheel fork, said main frameincluding chainstays; and a parallelogram-shaped suspension systemattached to a rear end of said chainstays of said main frame, saidparallelogram-shaped suspension system including: a rear fastening partattached to said rear end of said chainstays, said rear fastening parthaving a first pair of bearing bolts; a wheelholder for holding a rearwheel of the two-wheeled vehicle, said wheelholder having a second pairof bearing bolts; a first bar having a first end pivotably connected toa first one of said first pair of bearing bolts and having a second endpivotably connected to a first one of said second pair of bearing bolts;a second bar having a first end pivotably connected to a second one ofsaid first pair of bearing bolts and having a second end pivotablyconnected to a second one of said second pair of bearing bolts, saidfirst bar and said second bar having substantially equal lengths andbeing arranged substantially parallel, said first bar and said secondbar being arranged so as to extend at a downward incline from said rearfastening part towards a rear of said frame assembly; a spring devicebetween said rear fastening part and said wheelholder so as to extenddownward toward an axle of the rear wheel to thereby generate a springforce; and a power transmission device for transmitting power from afirst cogwheel mounted to said rear fastening part to a second cogwheelmounted to the rear wheel.
 2. The frame assembly of claim 1, whereinsaid spring device includes a pre-tensioning wheel operable to adjust acompression of a spring of said spring device so as to adjust apre-tension of said spring.
 3. The frame assembly of claim 1, whereinsaid power transmission device comprises a chain linking said firstcogwheel and said second cogwheel, said parallelogram-shaped suspensionsystem further including a freewheel mounted to said rear fasteningpart, said freewheel comprising a plurality of cogwheels including saidfirst cogwheel.
 4. The frame assembly of claim 3, wherein said freewheelis mounted to said rear fastening part by one of said first pair ofbearing bolts.
 5. The frame assembly of claim 1, wherein said chainstaysare arranged so as to extend along only one side of the rear wheel. 6.The frame assembly of claim 1, wherein said spring device of saidparallelogram-shaped suspension system includes a spring and anadjustment device at an end of said spring, said adjustment device beingoperable to displace said end of said spring transversely relative to alongitudinal axis of said spring.
 7. The frame assembly of claim 1,wherein said frame assembly further comprises a crank set and a cardantransmission for transmitting power from said crank set to said firstcogwheel, said cardan transmission including gimbals having differentlengths.
 8. The frame assembly of claim 1, wherein said frame assemblyfurther comprises a crank set and a cardan transmission, saidparallelogram-shaped suspension system further including a freewheelmounted to said rear fastening part, said cardan transmission beingoperable to transmit power from said crank set to said freewheel.
 9. Theframe assembly of claim 1, wherein said parallelogram-shaped suspensionsystem further includes a torsion spring having an arm resting against adisplaceable projection of at least one of said first bar and saidsecond bar, said displaceable projection being operable to move by awire connected to a lever.
 10. A frame assembly for a two-wheeledvehicle, comprising: chainstays; and a suspension system attached to arear end of said chainstays, said suspension system including: a rearfastening part attached to said rear end of said chainstays, said rearfastening part having a first pair of bearing bolts; a wheelholder forholding a rear wheel of the two-wheeled vehicle, said wheelholder havinga second pair of bearing bolts; a first bar having a first end pivotablyconnected to a first one of said first pair of bearing bolts and havinga second end pivotably connected to a first one of said second pair ofbearing bolts; a second bar having a first end pivotably connected to asecond one of said first pair of bearing bolts and having a second endpivotably connected to a second one of said second pair of bearingbolts, said first bar and said second bar having substantially equallengths and being arranged substantially parallel, said first bar andsaid second bar being arranged so as to extend at a downward inclinefrom said rear fastening part towards a rear of said frame assembly; aspring device between said rear fastening part and said wheelholder soas to extend downward toward an axle of the rear wheel to therebygenerate a spring force; and a power transmission device fortransmitting power from a first cogwheel mounted to said rear fasteningpart to a second cogwheel mounted to the rear wheel.
 11. The frameassembly of claim 10, wherein said power transmission device comprises achain linking said first cogwheel and said second cogwheel, saidsuspension system further including a freewheel mounted to said rearfastening part, said freewheel comprising a plurality of cogwheelsincluding said first cogwheel.
 12. The frame assembly of claim 10,wherein said spring device of said suspension system includes a springand an adjustment device at an end of said spring, said adjustmentdevice being operable to displace said end of said spring transverselyrelative to a longitudinal axis of said spring.
 13. The frame assemblyof claim 10, wherein said frame assembly further comprises a crank setand a cardan transmission for transmitting power from said crank set tosaid first cogwheel, said cardan transmission including gimbals havingdifferent lengths.
 14. The frame assembly of claim 10, wherein saidframe assembly further comprises a crank set and a cardan transmission,said suspension system further including a freewheel mounted to saidrear fastening part, said cardan transmission being operable to transmitpower from said crank set to said freewheel.
 15. The frame assembly ofclaim 10, wherein said suspension system further includes a torsionspring having an arm resting against a displaceable projection of atleast one of said first bar and said second bar, said displaceableprojection being operable to move by a wire connected to a lever.